1. Field of the Invention
The present invention generally relates to the field of wireless communications networks, particularly but not exclusively to mobile telephony networks (Public Land Mobile Networks—PLMNs), even more particularly second-generation (2G) PLMNs like those complying with the GSM (Global System for Mobile communications) standard and, specifically, to 2.5G PLMNs, i.e. 2G PLMNs enhanced with GPRS (General Packet Radio Service) and EDGE (Enhanced Data rates for Global Evolution) technologies, including the so-called EGPRS (Enhanced GPRS) PLMNs. Specifically, the invention relates to a method for discriminating users in the provisioning of network services, and to a PLMN implementing the method.
2. Description of Related Art
Mobile telephony networks, initially conceived for enabling voice communications, similar to the wired, Public Switched Telephone Networks (PSTNs), but between mobile users, have experienced an enormous spread, especially after the introduction of 2G mobile telephony networks, and particularly digital mobile cellular networks such as those complying with the GSM standard (and counterpart standards).
However, these 2G cellular networks, albeit satisfactory for voice communication, offer limited, non-versatile and non-cost effective data exchange capabilities.
Similarly to the plain old PSTNs, 2G mobile telephony networks are in fact Circuit-Switched (CS) networks, which offer limited bandwidth that can be allocated for a given user due to the constraints to the A interface (GSM interface between the BSS Base Station Subsystem—and the MSC—Mobile Switching Center), based on 64 kbps data transfer. On the contrary, data communications networks, such as computer networks and, among them, the Internet, adopt Packet-Switched (PS) schemes (they are also referred to as packet data networks), which allow much higher data transfer rates.
Some solutions have been proposed to overcome the limitations of conventional, CS mobile telephony networks such as the GSM networks, so as to enable users of mobile terminals (hereinafter, mobile stations) efficiently exploiting services offered through the Internet or other packet data networks.
One of the solutions that has gained great popularity is GPRS, a digital mobile radio service compatible with the GSM standard architecture, which requires the deployment of new nodes in the core network, namely the SGSN (Serving GPRS Support Node) and the GGSN (Gateway GPRS Support Node). GPRS enables more radio-versatile and cost-effective data transfer at a speed which may be higher than that allowed by pure GSM. Essentially, GPRS can be viewed as a GSM add-up that supports and enables packet-based data communication, and is a ready-at-hand solution for enhancing the data exchange capabilities of already existing GSM networks. As far as the radio frequency layer is concerned, GPRS completely relies on the GSM standard, preserving also the base-band burst formatting and the Gaussian Minimum Shift Keying (GMSK) modulation scheme adopted in the GSM standard.
A further enhancement of the transmission rate and of the efficiency of use of the licensed spectrum is represented by the EDGE technology, which is a step forward before the introduction of Wideband Code Division Multiple Access (WCDMA) systems adopted in third-generation (3G) mobile telephony networks like those complying with the Universal Mobile Telecommunications System (UMTS) standard. The EDGE technology introduces another modulation technique, i.e. 8-PSK (8-state Phase Shift Keying) and new channel coding schemes, which can be used to transmit both PS data and CS voice and data services.
The performances of GSM networks enhanced with GPRS and EGPRS (Enhanced GPRS) are such that they are for the moment not expected to be rendered obsolete by introduction of WCDMA networks, rather a coexistence of the two types of networks is believed to be most probable, even in more advanced stages of the deployment of WCDMA networks. For example, network operators not in possession of a license for WCDMA transmissions may find in EGPRS deployment a way to stay in the business, or EGPRS networks may provide coverage in geographic areas wherein a coverage by a WCDMA network is not practical or not cost-effective.
The EGPRS functionality relies on the same architecture as GPRS does. In spite of the changes to the radio interface, the same layer structure for signaling and data as for GPRS has been retained for EGPRS. In particular, the logical channels that have been introduced for GPRS are reused for EGPRS. Data is still transferred over PDTCH (Packet Data Traffic CHannel), whereas associated signaling is transmitted over PACCH (Packet Associated Control CHannel). The broadcast and control channels are also the same.
In EGPRS networks, the link quality control functionality has a fundamental role. In EGPRS, nine MCSs (Modulation and Coding Schemes) are introduced. The lowest numbered 4 MCSs are characterized by the use of GMSK modulation, while the 5 highest numbered MCSs use the 8-PSK modulation scheme. The link quality control functionality allows the full exploitation of the radio capability, by selecting the most appropriate MCS depending on the measurements of the radio quality performed by the terminal and reported to the network, and performed by the network itself.
An advantage of EGPRS networks is that they are able to support EGPRS-capable mobile stations, while retaining the capability of supporting GPRS-capable only mobile stations as well. Throughout the present document, by EGPRS-capable mobile station is intended to refer to a mobile station that is capable of accessing both GPRS and EGPRS network services. By GPRS-capable mobile station it is instead intended to refer to a mobile station that supports GPRS only.
From the radio bearer viewpoint, EGPRS-capable mobile stations may benefit from the use of 8-PSK radio bearers, whereas GPRS-capable mobile stations can only be allocated on GMSK radio bearers. Thanks to the enhanced data transfer capabilities offered by the EDGE technology, EGPRS networks are in principle capable of offering high Quality of Service (QoS).
Control of the QoS is an issue already faced in the art.
For example, the International application WO 2004/029854, entitled “Enhanced QoS control”, discloses a method for providing services to a user equipment, including providing a policy decision entity with subscriber information (regarding permitted conditions for the users to obtain the services) retrieved from a database; providing service information from at least one network or server, regarding service offered by the at least one network or server to the user equipment, forming policy rules at the policy decision entity based upon the subscriber information and the service information. A requesting user equipment transmits a request for service to the communications network; such request is processed by the policy decision entity in accordance with the policy rules to determine whether the service is to be allowed and, if the service is allowed, characteristics of the service to be provided to the requesting user equipment. The policy enforcement entity enforces at least one characteristic of an allowed service upon the communication network to ensure that the allowed service obtained by the requesting user equipment has the at least one characteristic of the allowed service.
The International application WO 2004/100595, entitled “Service restriction in mobile communication networks”, describes solutions that enable 3 G operators to identify the location of their subscribers (at a country level), the serving operator name and the access technology (i.e., 2.5G or 3G) supported by the serving network, so as to control access to contents/services taking into account rights and legal restrictions applicable outside the home country and the level of QoS provided by the serving network.